Corporate Author : NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) RADIO AND ELECTRICAL ENGINEERING DIV

Personal Author(s) : Rolfe,J.

Report Date : 30 NOV 1964

Pagination or Media Count : 1

Abstract : A platinum alloy crucible has been used in a crystalpulling apparatus for the growth of alkali halide single crystals. The addition of a conical top to the normal hemispherical or cylindrical crucible has three advantages. (1) If the crucible is heaped full of powdered alkali halide initially, the top surface of the melt will be just below the junction between the conical and the cylindrical part. (2) The crucible becomes very rigid and easily able to withstand the stresses caused by contraction of the alkali halide on cooling. (3) The conical top, made springy by 3-mm-deep cuts all round, fitted snugly into the inside of a 57-mm-o.d. Vycor tube used for a crucible enclosure, conforming to the non-circular cross section of the tube, providing a firm centering for the crucible, and preventing convection currents flowing upwards between the crucible and the enclosure.